I like the cool EO tech sights used by the US Armed Forces. They are robust & hold up to rough conditions. See; www.brownells.com www.uscav.com www.policeHQ.com www.midwayusa.com
. Brownells also markets a catalog just for AR/M4/M16 type rifles. They are a top shooting industry/gun owner resource.
Mag-Pul is highly rated for magazines too but I saw a cool AR polymer magazine that goes from green to red so you can check at a glance how many rounds are left.